Distributed power harvesting systems using DC power sources

• US 9,948,233 B2
• Filed: 07/27/2015
• Issued: 04/17/2018
• Est. Priority Date: 12/06/2006
• Status: Active Grant

• Current Assignee: Solaredge Technologies Incorporated
• Original Assignee: Solaredge Technologies Incorporated
• Inventors: Adest, Meir, Handelsman, Lior, Galin, Yoav, Fishelov, Amir, Sella, Guy, Gazit, Meir, Yoscovich, Ilan, Binder, Yaron
• Primary Examiner(s): Nguyen, Hai L
• Application Number:
  US14/809,511
• Publication Number:
  US 20150333692A1
• Time in Patent Office: 995 Days
• CPC Class Codes: H01L 31/02021 for solar cells electrical connection means, e.g. junction boxes, specially adapted for structural association with photovoltaic modules H02S40/34
• CPC Class Codes: H02J 1/102 being switching converters H02J1/108, H02J1/12 take precedence
• CPC Class Codes: H02J 2300/24 of photovoltaic origin
• CPC Class Codes: H02J 2300/26 involving maximum power point tracking control for photovoltaic sources maximum power point systems in particular G05F1/67
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/46 Controlling of the sharing of output between the generators, converters, or transformers
• CPC Class Codes: H02J 7/35 with light sensitive cells
• CPC Class Codes: H02S 40/34 comprising specially adapted electrical connection means to be structurally associated with the PV module, e.g. junction boxes
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

A photovoltaic panel with multiple photovoltaic sub-strings including serially-connected photovoltaic cells and having direct current (DC) outputs adapted for interconnection in parallel into a parallel-connected DC power source. A direct current (DC) power converter including input terminals and output terminals is adapted for coupling to the parallel-connected DC power source and for converting an input power received at the input terminals to an output power at the output terminals. The direct current (DC) power converter optionally has a control loop configured to set the input power received at the input terminals according to a previously determined criterion. The control loop may be adapted to receive a feedback signal from the input terminals for maximizing the input power. A bypass diode is typically connected in shunt across the input terminals of the converter. The bypass diode functions by passing current during a failure of any of the sub-strings and/or a partial shading of the sub-strings. The bypass diode may be a single bypass diode connected across the parallel-connected DC power source. The DC power converter may convert the input power at high current to the output power at a lower current. The output terminals may be connectible with wire cables to a load, and the DC power converter is configured to reduce energy loss through the wire cables to the load.

Claims

1. A photovoltaic panel comprising:

a plurality of photovoltaic power sources connected in parallel across power source terminals;

a direct current power converter coupled to the power source terminals, wherein the direct current power converter comprises output terminals and one or more of a capacitor, an inductor, and a transistor, wherein the direct current power converter is configured to convert input power received at the power source terminals to an output power at the output terminals; and

a bypass diode connected in shunt across the power source terminals.

2. The photovoltaic panel of claim 1, wherein the direct current power converter comprises a controller and a control loop coupled to at least one of the power source terminals, wherein the controller is configured to set, using the control loop, a voltage or a current at the power source terminals according to a previously determined criterion.

3. The photovoltaic panel of claim 2, wherein previously determined criterion is a maximum power point of the plurality of photovoltaic power sources connected in parallel.

4. The photovoltaic panel of claim 1, wherein the direct current power converter comprises a controller and a control loop coupled to at least one of the power source terminals, wherein the controller is configured to maximize, using the control loop, the input power.

5. The photovoltaic panel of claim 1, wherein the bypass diode is a single bypass diode connected across the power source terminals.

6. The photovoltaic panel of claim 1, wherein the direct current power converter comprises a buck converter serially connected to a boost converter.

7. A method comprising:

connecting a plurality of photovoltaic power sources in parallel across input terminals of a direct current power converter; and

attaching a bypass diode in shunt across the input terminals.

8. The method according to claim 7, comprising:

converting, with the direct current power converter, source power received from the plurality of photovoltaic power sources on the input terminals to output power on output terminals of the direct current power converter.

9. The method according to claim 8, comprising:

limiting output voltage on the output terminals until a predetermined minimum load is detected on the output terminals.

10. The method according to claim 8, comprising:

maximizing the source power received on the input terminals according to a maximum power point tracking control loop.

11. The method according to claim 10, comprising:

connecting the output terminals of the direct current power converter in series with output terminals of one or more other direct current power converters to form a series string.

12. The method according to claim 11, comprising:

controlling a voltage across the series string to a predetermined value.

13. The method according to claim 11, comprising:

inverting, with an inverter, string power received from the series string to alternating current power.

14. The method according to claim 13, comprising:

controlling a voltage across the series string to an input voltage to less than an operational rating of components within the inverter.

15. The method according to claim 11, comprising:

bypassing, through the bypass diode, current in response to a failure of any of the plurality of photovoltaic power sources or a shading of one or more of the plurality of photovoltaic power sources.

16. A system comprising:

a plurality of photovoltaic assemblies each comprising;

a plurality of photovoltaic sources, a direct current power converter, a diode, and output terminals, wherein the plurality of photovoltaic sources are connected in parallel to an input of the direct current power converter, the diode is connected across the input of the direct current power converter, and the output terminals are connected to an output of the direct current power converter; and

an inverter comprising inverter input terminals, wherein the plurality of photovoltaic assemblies are connected in a series string at their output terminals, and wherein the inverter input terminals are connected to the series string.

17. The system according to claim 16, wherein the inverter comprises a control loop, wherein the inverter is configured to control, using the control loop, a voltage on the inverter input terminals to a predetermined value.

18. The system according to claim 16, wherein the inverter comprises a control loop, wherein the inverter is configured to control, using the control loop, a voltage on the inverter input terminals to less than an operational rating of components within the inverter.

19. The system according to claim 16, wherein the direct current power converter in each of the plurality of photovoltaic assemblies comprises a controller and a control loop, wherein the controller is configured to set, using the control loop, a voltage or a current at its input according to a previously determined criterion.

20. The system according to claim 19, wherein the previously determined criterion comprises a maximum power point algorithm.